Laboratory and Theoretical Evaluation of Gelation Time Data for Water-Based Polymer Systems for Water Control

This article presents the evaluation and modeling of gelation-time data generated for four different water-based polymer systems used in the oil industry as sealants to shut off the undesired water production from hydrocarbon reservoirs. This article focuses primarily on the measurement and analysis of gelation time provided by each system at different temperature ranges. Each system presented in this article exhibits a different gelation mechanism. Gelation time for each system was measured as a function of temperature, activator concentration, polymer concentration, crosslinker concentration, salinity percent of mixing brine, and/or pH of solution. Methodologies used for gelation-time measurement and laboratory results are discussed. This article presents an investigation of temperature dependence of gelation time for each system that was analyzed and successfully correlated using an Arrhenius-type equation. The analysis of gelation-time data using the Arrhenius-type equation reveals and confirms the different gelation mechanisms working among the systems.     

Scanning Tunneling Spectroscopic Studies of the Pairing State of Cuprate Superconductors

Quasiparticle tunneling spectra of both hole-doped (p-type) and electron-doped (n-type) cuprates are studied using a low-temperature scanning tunneling microscope. The results reveal that neither the pairing symmetry nor the pseudogap phenomenon is universal among all cuprates, and that the response of n-type cuprates to quantum impurities is drastically different from that of the p-type cuprates. The only ubiquitous features among all cuprates appear to be the strong electronic correlation and the nearest-neighbor antiferromagnetic Cu²⁺-Cu²⁺ coupling in the CuO₂ planes.     

The Internationalization of an Undergraduate Program Using Reciprocal Distance Education*

The design and construction industries in the United States have become increasingly global and multidisciplinary over the last two decades. This emphasis will continue to expand even more rapidly in the near future. Undergraduate classes must be designed to reflect this tendency and introduce students to the tools and cultural diversity needed to compete in this environment in the future. This paper presents a model containing three distinct components for adding an international dimension to Architectural and Construction Science programs at Texas A&M University. The three components require varying degrees of commitment to an international dimension. The components are: 1) Insertion of an International Dimension at the Syllabus Level, 2) Integration of an International Dimension at the Curricular Level, and 3) Immersion in a Foreign Instructional Environment. The insertion and integrated components rely on the Internet and videoconferencing technology. These two components have come to be known as the “Reciprocal Distance Education Model.” The third component of the model is a blend of traditional study abroad programs with international internships and reciprocal student exchange programs.     

Analysis of Particle Transport and Deposition of Micron-Sized Particles in a 90° Bend Using a Two-Fluid Eulerian–Eulerian Approach

Two-phase flows involving dispersed particle and droplet phases are common in a variety of natural and industrial processes, such as aerosols, blood flow, emulsions, and gas-catalyst systems. For sufficiently dilute particle/aerosol phases, a simplified one-way coupling is often assumed, in which the continuous primary phase is unaffected by the presence of the dispersed secondary phase and standard CFD methods can be applied. To predict the transport and deposition of the particle phase, typically a Lagrangian particle-tracking or Eulerian one-fluid/two-phase drift-flux approach is used. Here, a full two-fluid Eulerian modeling approach is presented for coarse particles (>1 μm), in which transport equations are numerically solved for both particle-phase continuity and particle-phase momentum. Simulation results were obtained for a laminar flow regime (Re 100 and 1000) in a 90° elbow, and the effects of grid topology and resolution were investigated. Additionally, gravity effects were considered for both Re cases. Results using this full two-fluid Eulerian approach were validated against experimental data and other computational studies. One key novel contribution of this work is presentation of a simple algorithm for stabilizing the Eulerian particle-phase equation. To the authors' knowledge, this is the first study documenting a full two-fluid Eulerian approach for dilute particle phases in laminar flow on unstructured (prism/tetrahedral) meshes. The results show the potential of the two-fluid approach for providing a useful alternative to the more typical Lagrangian approach for prediction of coarse-particle transport and wall deposition.

Copyright 2015 American Association for Aerosol Research     

Chromosomal mutations induced by triplex-forming oligonucleotides in mammalian cells

Specific recognition of a region of duplex DNA by triplex-forming oligonucleotides (TFOs) provides an attractive strategy for genetic manipulation. Based on this, we have investigated the ability of the triplex-directed approach to induce mutations at a chromosomal locus in living cells. A mouse fibroblast cell line was constructed containing multiple chromosomal copies of the lambdasupFG1 vector carrying the supFG1 mutation-reporter gene. Cells were treated with specific (psoAG30) or control (psoSCR30) psoralen-conjugated TFOs in the presence and absence of UVA irradiation. The results demonstrated a 6- to 10-fold induction of supFG1 mutations in the psoAG30-treated cells as compared with psoSCR30-treated or untreated control cells. Interestingly, UVA irradiation had no effect onthe mutation frequencies induced by the psoralen-conjugated TFOs, suggesting a triplex-mediated but photoproduct-independent process of mutagenesis. Sequencing data were consistent with this finding since the expected T.A-->A.T transversions at the predicted psoralen crosslinking site were not detected. However, insertions and deletions were detected within the triplex binding site, indicating a TFO-specific induction of mutagenesis. This result demonstrates the ability of triplex-forming oligonucleotides to influence mutation frequencies at a specific site in a mammalian chromosome.     

Titanium dioxide/amine hybrid nanotubes. Optical properties and behavior as lithium-ion electrode

Titanium dioxide based tubular nanocomposites containing long-chain amines were prepared by hydrothermal reaction of anatase with neutral surfactants, dodecylamine and octadecylamine, under strong alkaline conditions. Morphologically pure phases are obtained after reaction times of about 50 h at 130 °C. Dodecylamine derivates are structural and thermally more fragile than those with octadecylamine. Under more drastic reaction conditions, 72 h at 150 °C, amine is segregated leading to almost pure inorganic nanotubes or fibers for octadecyl and dodecyl derivatives respectively. The products characterized by electron microscopy, X-ray diffraction, FT-IR and elemental analysis are constituted by the hydrogen titanat H₂Ti₃O₇. Diffuse reflectance spectra reveal the products present typical size-dependent optical properties. The photoluminescence spectra are qualitatively similar to that of anatase dominated by the presence of traps located in the band gap. The electrochemical lithium intercalation and lithium diffusion coefficients of the products were studied by intermittent galvanostatic method and galvanostatic pulse relaxation technique respectively. Products were tested in a lithium cell using the nanocomposites as the active material of the positive electrode. The hybrid dodecylamine derivative shows a first cycle irreversible capacity of 219 mAh/g, and a capacity of 113 mAh/g after the 7th cycle which results improved in comparison with those reported for H₂Ti₃O₇ electrodes, thus pointing to a protective effect of the amine.     

Warpage Behavior of 7075 Aluminum Alloy Extrusions

Extruded I sections of 7075-T6 aluminum were machined into four different sections shapes: L, short depth L, T, and short depth T. The furnace was preheated to 416 °C (780 °F) and the samples were placed inside. The temperature was raised to 471 °C (880 °F) and then the samples were quenched in either a 30% polyalkylene Glycol solution or water, both at 15 °C (59 °F). Points on the distorted samples were recorded before and after the solution treatment; the difference between the measurements indicated the extent of warpage.     

4-Quinolinone alkaloids from Dictyoloma peruviana

The stem-bark of Dictyoloma peruviana yielded two new piperidino [1,2-a] 4-quinolinones, dictyolomide A and dictyolomide B. Their structures were established by NMR spectroscopy.     

Inactivation of beta-lactamase from Shigella flexneri UCSF-129 by BRL 42715, a potent inhibitor

The effect of a powerful inhibitor, BRL 42715, on beta-lactamase from Shigella flexneri UCSF-129, to overcome the problem of shigellosis and its resistance to ampicillin, was studied. The I50 was determined for BRL 42715 [C6-(N1-methyl-1,2,3 triazolylmethylene)penem] as 0.0049 microgram/ml being 20-fold lower than the best inhibitor, 6-beta-iodopenicillanic acid, previously reported. The MIC fell from 2,048 to 2 micrograms/ml in the presence of 1 microgram/ml of BRL 42715. The synergism of the ampicillin plus this inhibitor lasted for 9 h. BRL 42715 is an irreversible inhibitor, according to the dialysis results, and a substrate analogue.